1. Field of the Invention
The present invention relates to a method and apparatus for displaying pictures on a plasma display panel (PDP), and more particularly to a method and apparatus for reducing flicker when displaying pictures on a PDP, based on an input phase alternation line (PAL) video signal of 50 Hz.
2. Description of the Related Art
Recently, flat panel displays, such as liquid crystal displays (LCDs), field emission displays (FEDs) and PDPs, have been actively developed. The PDPs are advantageous over the other flat panel displays in regard to their high luminance, high luminous efficiency and wide viewing angle. Accordingly, the PDPs are being highlighted as a substitute for conventional cathode ray tubes (CRTs) for large-screen displays of more than 40 inches.
The PDPs are flat panel displays that use plasma generated by gas discharge to display characters or images. The PDPs include, according to their size, more than several tens to millions of pixels arranged in the form of a matrix. These PDPs are classified into a direct current (DC) type and an alternating current (AC) type according to patterns of waveforms of driving voltages applied thereto and discharge cell structures thereof.
Such PDPs must realize gradation display so that they function as color display devices. For the gradation display, a method has been used in which one field is divided into a plurality of sub-fields, and the sub-fields are controlled in a time-sharing manner.
Meanwhile, flickers may be generated in the gray scale expression in PDPs. Such flickers have close relation with the visual characteristics of human eyes. Generally, flickers may be more easily recognizable by human eyes on a larger screen or at a lower frequency. Where images of PAL video signals are displayed on a PDP, a large amount of flickers are generated because both the above-mentioned conditions are required.
Thus, when a PDP is driven at a vertical frequency of 50 Hz, using a general sub-field arrangement used in PDPs, for example, a lowest ascending-order arrangement or a lowest descending-order arrangement, a large amount of flickers may be generated.
It is impossible to adjust the screen size in association with the large-screen requirement, which is one of the above-mentioned two conditions causing generation of flickers. Accordingly, reduction of flickers may be achieved by adjusting the frequency, which is also associated with generation of flickers.